For many years, the standard apparatus for performing the evacuation of the pleural cavity was a drainage system known as the "3-bottle set-up" which includes a collection bottle, a water seal bottle and a suction control bottle. A catheter runs from the patient's pleural cavity to the collection bottle, and the suction bottle is connected by a tube to a suction source. The three bottles are connected in series by various tubes to apply suction to the pleural cavity to withdraw fluid and air and thereafter discharge the same into the collection bottle. Gases entering the collection bottle bubble through water in the water seal bottle. The water in the water seal also usually prevents the back flow of air into the chest cavity.
Suction pressure is usually provided by a central vacuum supply in a hospital so as to permit withdrawal of fluids such as blood, water and gas from a patient's pleural cavity by establishing a pressure differential between the suction source and the internal pressure in the patient. Such suction pressure and pressure differentials must be precisely maintained because of the dangerous conditions which could result if unduly high or low pressure differentials should occur. However, the bottles typically were placed on a support such as a table or floor and could be knocked over and the tubes pulled out accidentally.
The 3-bottle set-up lost favor with the introduction of an underwater seal drainage system sold under the name "Pleur-evac".RTM. in 1966 by Deknatel Inc..sup.1 U.S. Pat. Nos. 3,363,626; 3,363,627; 3,559,647; 3,683,913; 3,782,497; 4,258,824; and Re. 29,877 are directed to various aspects of the Pleur-evac.RTM. system which over the years has provided improvements that eliminated various shortcomings of the 3-bottle set-up. These improvements have included the elimination of variations in the 3-bottle set-up that existed between different manufacturers, hospitals, and hospital laboratories, such variations including bottle size, tube length and diameter, stopper material and the like. FNT .sup.1 A more detailed description of the need for and the proper use of chest drainage devices is presented in the Deknatel Inc. Pleur-evac.RTM. publication entitled "Physiology of the Chest and Thoracic Catheters; Chest Drainage Systems No. 1 of a series from Deknatel" (1985) which is incorporated herein in its entirety.
Among the features of the Pleur-evac.RTM. system which provide its improved performance are employment of 3-bottle techniques in a single, pre-formed, self-contained unit. The desired values of suction are generally established by the levels of water in the suction control bottle and the water seal bottle. These levels are filled according to specified values prior to the application of the system to the patient. A special valve referred to as the "High Negativity Valve" is included which is employed when the patient's negativity becomes sufficient to threaten loss of the water seal. Also, a "Positive Pressure Release Valve" in the large arm of the water seal chamber works to prevent a tension pneumothorax when pressure in the large arm of the water seal exceeds a prescribed value because of suction malfunction, accidental clamping or occlusion of the suction tube. The Pleur-evac.RTM.system is disposable and helps in the battle to control cross-contamination.
The Pleur-evac.RTM. is provided with hanger hooks to permit supporting the device, for example, from a hospital bed. However, the hooks are easily removable from the device and are loosely attached which still permit dislodging the Pleur-evac.RTM. from its support by inadvertent jostling and the like.
Despite the advantages of the Pleur-evac.RTM. system over the 3-bottle set-up and the general acceptance of the device in the medical community, there remains a continuing need to improve the convenience and performance of chest drainage systems and to render such systems compact.
We have invented an improved hanger means for a drainage device which provides additional improvements to presently available devices.